Wafer boat handling device, vertical batch furnace and method

ABSTRACT

A wafer boat handling device, configured to be positioned under a process chamber of a vertical batch furnace. The wafer boat handling device comprises a main housing having a wall defining and bounding a wafer boat handling space, and a boat transporter comprising a wafer boat support for supporting a wafer boat and configured to transport the wafer boat to a cooldown position within the wafer boat handling space. A part of the wall adjacent the cooldown position is a wall part with a heat radiation surface absorptance of at least 0.60 so as to withdraw heat from the wafer boat which is in the cooldown position by means of heat radiation absorption.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 62/848,758 filed May 16, 2019 titled WAFER BOAT HANDLING DEVICE, VERTICAL BATCH FURNACE AND METHOD, the disclosures of which are hereby incorporated by reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a wafer boat handling device. The wafer boat handling device may be configured to be positioned under a process chamber of a vertical batch furnace for processing a plurality of wafers accommodated in a wafer boat. The present disclosure furthermore relates to a vertical batch furnace assembly comprising said wafer boat handling device. The present disclosure also relates to a method for cooling a wafer boat in the wafer boat handling device.

BACKGROUND

Wafer boat handling devices, which may be configured to be positioned under a process chamber of a vertical batch furnace may be used for processing a plurality of wafers accommodated in a wafer boat. Wafer boat handling may be configured to vertically transport a wafer boat to a process chamber of said batch furnace, and to receive the wafer boat from the process chamber. The wafer boats received from the batch furnace may be hot and may need to be cooled down at a cooldown position before the processed wafers can be taken out of the wafer boat.

In wafer boat handling devices, this cooling may be improved by a circulation of air or gas which may be cooled by using a heat-exchanger.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

It may be an object to provide an improved wafer boat handling device which cools the wafer boat.

The part of the wall adjacent the cool down position may typically be made of stainless steel which may have a heat radiation surface absorptance of 0.3-0.4. The heat radiation surface absorptance is the ratio of the absorbed heat radiation to the incident heat radiation. By having a part of the wall having a heat radiation surface absorptance of 0.3-0.4 a substantial portion of the incident heat may be reflected away from the wall back to the wafer boat which may not help in cooling down the wafer boat.

To that end, there may be provided a wafer boat handling device. More particularly, there may be provided a wafer boat handling device, configured to be positioned under a process chamber of a vertical batch furnace. The wafer boat handling device may comprise a main housing, and a boat transporter. The main housing may have a wall defining and bounding a wafer boat handling space. The boat transporter may comprise at least one wafer boat support for supporting a wafer boat and may be configured to transport the wafer boat to a cooldown position within the wafer boat handling space. A part of the wall adjacent the cool down position may be a wall part having a heat radiation surface absorptance of at least 0.60 so as to absorb heat from the wafer boat which is in the cooldown position by means of heat radiation absorption. The heat radiation surface absorptance is the ratio of the absorbed heat radiation to the incident heat radiation.

By virtue of the wall part having the heat radiation surface absorbance of at least 0.6, the reflection of radiation heat may be greatly reduced. As a consequence the wafer boat may cool down more quickly. This means that the processed wafers in the wafer boat may be taken out sooner and the wafer boat handling device runs more efficiently.

According to a further embodiment, there is provided a vertical batch furnace assembly comprising a process chamber for processing wafers accommodated in a wafer boat and a wafer boat handling device according to the invention. The wafer boat handling device is positioned under the process chamber. The vertical batch furnace further comprises a vertical wafer boat lift assembly configured to transfer a wafer boat from the wafer boat handling device to the process chamber and vice versa.

The vertical batch furnace may have the same advantages as those which have been described above in relation to the wafer boat handing device.

Finally, the invention provides a method for cooling a wafer boat in a wafer boat handling device. More particularly, the method comprises: providing a wafer boat handling device according to the invention, providing a wafer boat on the at least one wafer boat support of the wafer boat handling device, transporting the wafer boat to the cooldown position, and absorbing heat radiation from the wafer boat by means of the wall part.

The method has the same advantages as those which have been described above in relation to the wafer boat handing device and the vertical batch furnace.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

Various embodiments are claimed in the dependent claims, which will be further elucidated with reference to an example shown in the figures. The embodiments may be combined or may be applied separate from each other.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE FIGURES

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIG. 1 shows a perspective view of an example of the wafer boat handling device according to an embodiment; and

FIG. 2 shows a schematic top view of an example of the wafer boat handling device according to an embodiment.

DETAILED DESCRIPTION OF THE FIGURES

In this application similar or corresponding features are denoted by similar or corresponding reference signs. The description of the various embodiments is not limited to the example shown in the figures and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiments, but are included to elucidate the embodiments by referring to the example shown in the figures.

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below. The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “wafer” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit, or a film may be formed.

In the most general term the present disclosure provides a wafer boat handling device 10, configured to be positioned under a process chamber of a vertical batch furnace. The vertical batch furnace may be configured for processing a plurality of wafers accommodated in a wafer boat 12. The wafer boat handling device 10 may comprise a main housing, and a boat transporter 20. The main housing 14 may have a wall 16 defining and bounding a wafer boat handling space 18. The boat transporter 20 may comprise at least one wafer boat support 22 for supporting a wafer boat 12 and may be configured to transport the wafer boat 12 to a cooldown position 24 within the wafer boat handling space 18. A part of the wall adjacent the cool down position 24 comprises a wall part 26 having a heat radiation surface absorptance of at least 0.6 so as to withdraw heat from the wafer boat 12 by means of heat radiation absorption. The heat radiation surface absorptance is the ratio of the absorbed heat radiation to the incident heat radiation. The wall part 26 may be from metal.

The wall part 26 adjacent the cool down position may have a heat radiation surface absorptance between 0.6 and 0.99. The heat radiation surface absorptance may vary as a function of a temperature of the wafer boat since that temperature influences the Infra Red spectrum. The heat radiation surface absorptance of the wall part 26 (at room temperature) may be between 0.6 and 0.99 when the wafer boat loaded with wafers is in a temperature range between 70 to 200 degrees Celsius. The heat radiation absorptance of the wall part 26 (at room temperature) may be between 0.65 and 0.95 when the wafer boat loaded with wafers is in a temperature range between 70 and 100 degrees Celsius.

Of course, at least the side of the wall part which is directed to the wafer boat handling space, in particular to the wafer boat which is in the cooldown position may have the heat radiation surface absorptance of at least 0.6 so as to withdraw heat from the wafer boat 12 by means of heat radiation absorption. The wafer boat may have a temperature between 25 to 800 degrees Celsius during cool down in the cool down position.

In an embodiment, the wall part 26 may be metal. The metal may comprise an anodized aluminum. The heat radiation surface absorptance of an anodized aluminum wall part may be between 0.6 and 0.99.

Alternatively or additionally, the wall part 26 may comprise a painted metal wall part. The heat radiation surface absorptance of a painted metal wall part may be between 0.6 and 0.99.

Consequently, both the anodized aluminum as well as a painted metal surface may provide an improved absorption of heat radiation. As a consequence the wafer boat may cool down more quickly, for example, from a temperature between 300 to 800 degrees Celsius, when the boat comes out of the furnace, to a temperature between 25 to 100 degrees Celsius, when cooldown may be finished. This means that the processed wafers in the wafer boat may be taken out sooner and the wafer boat handling device runs more efficiently.

In an embodiment, the wall part 26 may comprise a cooling channel 30 constructed and arranged to have, in use, a liquid coolant running there through to cool said wall part 26. By absorbing the heat radiation from the wafer boat 12, the wall part 26 may increase in temperature. By cooling the wall part 26 by means of liquid running through the cooling channel, the liquid coolant may dispose of the heat which is absorbed by the wall part 26. This prevents that the wall part 26 becomes too hot

In addition or alternatively to the cooling channel 30, the wall part 26 may be configured as a heat sink to draw heat from the wafer boat 12. To that end, the wall part 26 may have a thickness so that the wall part 26 operates as a heat sink.

Alternatively or in addition to that, an outer surface 62 of the wall part 26 which is directed away from the wafer boat handling space 18 may have a heat exchange surface enlarging shape so that the wall part 26 operates as a heat sink. The heat exchange surface enlarging shape includes at least one of fins, pins, holes, and a surface roughness. A heat sink is a passive heat exchanger that transfers heat. On the inner surface 28 of the wall part 26, which is directed to the wafer boat handling space 18, the wall part 26 absorbs the heat radiation from the wafer boat 12. On the outer surface 62 of the wall part 26 embodied as a heat sink, the wall part 26 may lead the absorbed heat away, for example by means of radiation and/or convection. The radiation and/or convection of the absorbed heat may be enhanced by the surface enlarging shape, such as fins, pins, holes, and/or surface roughness. The heat sink may include an active heat exchanger, such as the already mentioned cooling channel 30, but this need not be. The heat sink may comprise a passive heat exchanger such as a heat pipe.

In an embodiment, the boat transporter 20 may comprise a rotatable table 34 comprising the at least two wafer boat supports. The rotatable table 34 is rotatable within the main housing 14 around a central vertical axis 36 to be positionable in a number of rotational positions. A vertically extending wall structure 38 may be mounted on the rotatable table 34 and may at least partially bound, at each wafer boat support 22, a corresponding vertically extending wafer boat chamber 40. The rotatable table 34 may comprise for each wafer boat chamber 40 a rotational position in which the wafer boat chamber and the wafer boat accommodated therein is in the cooldown 24 position.

Various embodiments of the boat transporter 20 are known. In this embodiment the boat transporter 20 comprises the rotatable table 34, and the vertically extending wall structure 38, together also known as a carrousel. For cooling down the wafer boat 12, the rotatable table 34 may rotate a wafer support 22 thereof with the wafer boat 12 positioned thereon to the cooldown position 24. Other rotational positions to which a wafer boat chamber 40 and a wafer boat accommodated therein may be moved by rotation of the rotatable table 34 include a load/receive position for vertically loading the wafer boat 12 to the process chamber 66 and for receiving the wafer boat 12 from the process chamber 66, and a transfer position for transferring wafers from and to the wafer boat 12, possibly though an opening which is provided in the wall 16 of the main housing 14.

An advantage of using the rotatable table 34 with vertically extending wall structure 38 is that for each wafer boat chamber 40 which is created by the vertically extending wall structure 38 a mini-environment may be created. This means that a wafer boat 12 which is in a first wafer boat chamber 40 is not exposed to debris coming from a wafer boat 12 which is in a second wafer boat chamber 38. In fact, a conditioned mini-environment is created in each wafer boat chamber 40. This reduces the chance of contamination of the wafers considerably.

In an embodiment the wafer boat handling device may further comprise a gas circulation system 42 for supplying a gas to and withdrawing the gas from the wafer boat handling space 18 to create a mini-environment within the main housing 14 of the wafer boat handling device 10. The gas circulation system 42 may include a gas circulation system heat exchanger 44 for cooling down the gas which is supplied to the wafer boat handling space 18 so as to withdraw heat from the wafer boat 12 which is in the cooldown position 24 by means of convection.

The gas circulation system 42 provides a second way to cool down the wafer boat and the wafers which are in the wafer boat. The first way to cool down the wafer boat 12 with wafers is by means of absorption of heat radiation by means the wall part 26 having the heat radiation surface absorptance at least 0.60. The second way to cool down the wafer boat 12 with wafers is by means of heat convection. The heat convection is enhanced by supplying cooled down gas to the wafer boat handling device, in particular at least to the wafer boat chamber 40 which is in the cooldown position. Convection is used to transfer the heat from the wafer boat 12 and the wafers to the cooled down gas which is supplied by the gas circulation system 42. The application of two ways of withdrawing heat from the wafer boat with hot wafers enhances the cooling capacity of the wafer boat handling device 10 and thus reduces the cooling time.

In an embodiment the gas circulation system 42 may be configured to supply the gas at least to the wafer boat chamber 40 which is in the cooldown position 24. Not every wafer boat chamber 40 needs to be cooled. It may suffice to cool the wafer boat 12 with wafers which is in the cooldown position 24.

In an embodiment, the gas circulation system 42 may comprise a gas supply area, a gas discharge area 50, an inlet duct 54, an outlet duct 56, and a recirculation channel. The outlet duct 56 as shown in FIG. 2 is bounded by the vertically extending wall structure 38. In an alternative embodiment, the circumferential wall part 38 a of the vertically extending wall structure 38 may be omitted so that the outlet duct 56 is directly bounded by the wall 16 of the main housing 14. In that embodiment, the part of the wall 16 of the main housing 14 which bounds the outlet duct 56 which is associated with the wafer boat which is in the cooldown position may also have a heat radiation surface absorptance of at least 0.6 and in a further embodiment may comprise cooling channels. This embodiment may further improve the cooling effect. The outlet duct 56 may be embodied as a passage between the vertically extending wall structure 38 and the wall 16 of the main housing 14. The gas supply area 46 in each wafer boat chamber 40 may comprise a plurality of gas supply openings distributed in the vertically extending wall structure 38. The gas discharge area 50 in each wafer boat chamber 40, at least when the wafer boat chamber 40 is in the cooldown position 24, may comprise a plurality of gas discharge openings. The inlet duct 54 may be in fluid communication with the gas supply openings. The outlet duct 56 may be in fluid communication with the gas discharge openings. The recirculation channel may extend from the outlet duct 56 to the inlet duct 54 and may comprise at least one gas blower. The gas circulation system 42 thus forms a closed loop circulation system. The gas blower may blow the gas through the recirculation channel and thus through the gas circulation system 42 to cool at least the wafer boat 12 with wafers which is in the cooldown position. The inlet duct 54 and/or the outlet 56 may be created by the vertically extending wall structure 38. Both ducts 54, 56 will then rotate with the wafer boat chambers 40 on the rotatable table 34.

At least a part of the gas discharge area 50 comprising the plurality of gas discharge openings may be provided in the wall part 26 having the heat radiation surface absorptance of at least 0.60. In this way the outlet duct 56 may be constructed such that the outlet duck 56 need not to rotate with the rotatable table 34 but can be connected to the main housing 14. This makes the construction of the outlet duck 56 less technically challenging and thus cheaper.

In an embodiment, the cooling channel 30 may comprise a plurality of cooling channels 30 which are part of the gas circulation system heat exchanger 44. The plurality of cooling channels 30 thus may cool both the wall part 26 as well as the gas in the gas circulation system 42. The cooling capacity of the cooling channels 30 may be configured such that the heat radiation absorbed by the metal wall part 26 as well as the heat absorbed by the gas through convection is drained by the liquid coolant in the cooling channels 30. Thus, effective cooling is achieved.

In an embodiment, the vertically extending wall structure 38 may include reflection surfaces which are configured such as to reflect heat radiated by the wafer boat 12 in the direction of the wall part 26. The heat radiated from the wafer boat 12 will normally not only radiate towards the wall part 26 but throughout the entire circumference of the wafer boat 12. This means that also other parts of the wafer boat handing device 10 will receive this heat radiation. Instead of absorbing this heat radiation, the said reflection surfaces in the vertically extending wall structure 38 will reflect the heat radiation in the direction of the wall part 26. This enhances the absorption of heat radiation of the wall part 26 and thus increases the cooling efficiently of the wafer boat handling device.

The present disclosure also provides a vertical batch furnace assembly comprising a process chamber 66 for processing wafers accommodated in a wafer boat 12, a wafer boat handling device 10 according to the invention which is positioned under the process chamber 66, and a vertical wafer boat lift assembly 68 configured to transfer a wafer boat 12 from the wafer boat handling device 10 to the process chamber 66 and vice versa.

The effects and advantages of the vertical batch furnace assembly have been described in the summary section and these effects and advantages are inserted here by reference.

Finally, the present disclosure provides a method for cooling a wafer boat 12 in a wafer boat handling device 10. The method comprises providing a wafer boat handling device 10 according to the invention, providing a wafer boat 12 on the at least one wafer boat support 22 of the wafer boat handling device 10, transporting the wafer boat 12 to the cooldown position 24, and absorbing heat radiation from the wafer boat 12 by means of the wall part 26 having the heat radiation surface absorptance of at least 0.60.

The effects and advantages of the method have been described in the summary section and these effects and advantages are inserted here by reference.

In an embodiment the method further comprises cooling down a gas which is supplied to the wafer boat handling space 18 and withdrawing heat from the wafer boat 12 which is in the cooldown position 24 by means of convection.

In addition to cooling the wafer boat 12 by absorbing heat radiation, the cooled gas provides a second way to cool down the wafer boat 12, namely by the convention of heat through by means of cooled gas which is supplied to the wafer boat handling space 18. This further enhances the cooling capacity of the wafer boat handling device 10.

Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying drawings, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this description are not necessarily all referring to the same embodiment.

Furthermore, it is noted that particular features, structures, or characteristics of one or more of the various embodiments which are described above may be used implemented independently from one another and may be combined in any suitable manner to form new, not explicitly described embodiments. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments nor do they limit the claims. The reference numbers are solely used to clarify.

LEGEND

10—wafer boat handling device

12—wafer boat

14—main housing

16—wall

18—wafer boat handling space

20—boat transporter

22—wafer boat support

24—cooldown position

26—wall part

28—wall part inner surface

30—cooling channel

34—rotatable table

36—central vertical axis

38—vertically extending wall structure

40—wafer boat chamber

42—gas circulation system

44—gas circulation heat exchanger

46—gas supply area

50—gas discharge area

54—inlet duct

56—outlet duct

62—wall part outer surface

66—process chamber

68—vertical wafer boat lift assembly 

1. A wafer boat handling device, configured to be positioned under a process chamber of a vertical batch furnace, wherein the wafer boat handling device comprises: a main housing having a wall defining and bounding a wafer boat handling space; a boat transporter comprising at least one wafer boat support for supporting a wafer boat and configured to transport the wafer boat to a cooldown position within the wafer boat handling space; wherein a part of the wall adjacent the cooldown position is a wall part having a heat radiation surface absorptance of at least 0.6 so as to withdraw heat from the wafer boat which is in the cooldown position by means of heat radiation absorption.
 2. The wafer boat handling device according to claim 1, wherein the wall part is a metal wall part.
 3. The wafer boat handling device according to claim 2, wherein the metal wall part is an anodized aluminum wall part.
 4. The wafer boat handling device according to claim 1, wherein the wall part comprises a painted metal wall part.
 5. The wafer boat handling device according to claim 1, wherein the wall part comprises a cooling channel constructed and arranged to have, in use, a liquid coolant running there through to cool said wall part.
 6. The wafer boat handling device according to claim 1, wherein the boat transporter comprises: a rotatable table comprising at least two wafer boat supports, wherein the rotatable table is rotatable within the main housing around a central vertical axis to be positionable in a number of rotational positions; a vertically extending wall structure mounted on the rotatable table and at least partially bounding, at each wafer boat support, a corresponding vertically extending wafer boat chamber, wherein the rotatable table comprises for each wafer boat chamber a rotational position in which the wafer boat chamber and the wafer boat accommodated therein is in the cooldown position.
 7. The wafer boat handling device according to claim 1, further comprising: a gas circulation system for supplying a gas to and withdrawing the gas from the wafer boat handling space to create a mini-environment within the main housing of the wafer boat handling device, wherein the gas circulation system includes a gas circulation system heat exchanger for cooling down the gas which is supplied to the wafer boat handling space so as to withdraw heat from the wafer boat which is in the cooldown position by means of convection.
 8. The wafer boat handing device according to claim 6, further comprising: a gas circulation system for supplying a gas to and withdrawing the gas from the wafer boat handling space to create a mini-environment within the main housing of the wafer boat handling device, wherein the gas circulation system includes a gas circulation system heat exchanger for cooling down the gas which is supplied to the wafer boat handling space so as to withdraw heat from the wafer boat which is in the cooldown position by means of convection, and wherein the gas circulation system is configured to supply the gas at least to the wafer boat chamber which is in the cooldown position.
 9. The wafer boat handling device according to claims 8, wherein the gas circulation system comprises: a gas supply area in each wafer boat chamber comprising a plurality of gas supply openings distributed in the vertically extending wall structure; a gas discharge area in each wafer boat chamber, at least when the wafer boat chamber is in the cooldown position, wherein the gas discharge area comprises a plurality of gas discharge openings; an inlet duct which is in fluid communication with the gas supply openings; an outlet duct which is in fluid communication with the gas discharge openings; and a recirculation channel extending from the outlet duct to the inlet duct and comprising at least one gas blower.
 10. The wafer boat handling device according to claim 9, wherein at least a part of the gas discharge area comprising the plurality of gas discharge openings is provided in the wall part having the heat radiation surface absorptance of at least 0.6.
 11. The wafer boat handling device according to claim 5, wherein at least a part of the gas discharge area comprising the plurality of gas discharge openings is provided in the wall part having the heat radiation surface absorptance of at least 0.6, and wherein the cooling channel comprises a plurality of cooling channels which are part of the gas circulation system heat exchanger, wherein the cooling capacity of the cooling channels is configured such that the heat radiation absorbed by the wall part as well as the heat absorbed by the gas through convection is drained by the liquid coolant in the cooling channels.
 12. The wafer boat handling device according to claim 1, wherein the vertically extending wall structure includes reflection surfaces which are configured such as to reflect heat radiated by the wafer boat in the direction of the wall part.
 13. The wafer boat handling device according to claim 1, wherein the wall part has a thickness so that the wall part operates as a heat sink.
 14. The wafer boat handling device according to claim 1, wherein an outer surface of the wall part which is directed away from the wafer boat handling space has a heat exchange surface enlarging shape so that the wall part operates as a heat sink, wherein the heat exchange surface enlarging shape includes at least one of fins, pins, holes and a surface roughness.
 15. A vertical batch furnace assembly comprising: a process chamber for processing wafers accommodated in a wafer boat; a wafer boat handling device according to claim 1, wherein the wafer boat handling device is positioned under the process chamber; and a vertical wafer boat lift assembly configured to transfer a wafer boat from the wafer boat handling device to the process chamber and vice versa.
 16. A method for cooling a wafer boat in a wafer boat handling device, the method comprising: providing a wafer boat handling device according to claim 1; providing a wafer boat on the at least one wafer boat support of the wafer boat handling device; transporting the wafer boat to the cooldown position; and absorbing heat radiation from the wafer boat by means of the wall part having the heat radiation surface absorptance of at least 0.6.
 17. The method for cooling a wafer boat in a wafer handling device of claim 16, the method further comprising: cooling down a gas which is supplied to the wafer boat handling space; and withdrawing heat from the wafer boat which is in the cooldown position by means of convection.
 18. The wafer boat handling device according to claim 6, wherein the vertically extending wall structure includes reflection surfaces which are configured such as to reflect heat radiated by the wafer boat in the direction of the wall part. 